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<head><meta charset="utf-8"><title>Changes to the dep-graph on-disk representation · t-compiler/wg-incr-comp · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/index.html">t-compiler/wg-incr-comp</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html">Changes to the dep-graph on-disk representation</a></h3>

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<a name="231686202"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/231686202" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> cjgillot <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#231686202">(Mar 24 2021 at 18:34)</a>:</h4>
<p>FYI <span class="user-group-mention" data-user-group-id="3282">@wg-incr-comp</span>: I have a series of PRs changing the way the dep-graph is persisted on disk: <a href="https://github.com/rust-lang/rust/issues/82780">#82780</a>, <a href="https://github.com/rust-lang/rust/issues/83214">#83214</a> and <a href="https://github.com/rust-lang/rust/issues/83322">#83322</a>. <span class="user-mention" data-user-id="124287">@mw</span> has been reviewing the implementation. We would feel more comfortable merging early in the release cycle, and with a team sign-off. Please take a look and tell me if a MCP is required.</p>



<a name="231773428"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/231773428" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> mw <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#231773428">(Mar 25 2021 at 10:02)</a>:</h4>
<p>Yup, <a href="https://github.com/rust-lang/rust/issues/82780">#82780</a> is probably closest to being finished. It does not fundamentally change things - it just makes the compiler write the dep-graph to disk as it goes instead of all at once at the end. So I don't think an MCP is required (as long as the working group is aware of the changes).</p>



<a name="231773681"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/231773681" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> mw <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#231773681">(Mar 25 2021 at 10:04)</a>:</h4>
<p><a href="https://github.com/rust-lang/rust/issues/83214">#83214</a> is also something that makes a lot of sense. I haven't had time to review it in detail. I don't think this one requires an MCP.</p>



<a name="231774082"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/231774082" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> mw <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#231774082">(Mar 25 2021 at 10:07)</a>:</h4>
<p><a href="https://github.com/rust-lang/rust/issues/83322">#83322</a> I have not really looked at much. I think the general direction definitely makes sense but we'll need to gather some data on how it affects file sizes. In general, getting rid of the LEB128 encoding (at least for incr. comp. caches) is a good idea and opens things up for further optimizations.</p>



<a name="231774209"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/231774209" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> mw <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#231774209">(Mar 25 2021 at 10:08)</a>:</h4>
<p>Lots of great stuff from <span class="user-mention" data-user-id="248906">@cjgillot</span> lately! <span aria-label="smile" class="emoji emoji-1f642" role="img" title="smile">:smile:</span></p>



<a name="232394912"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/232394912" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> mw <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#232394912">(Mar 30 2021 at 09:06)</a>:</h4>
<p>Heads up! I plan to r+  <a href="https://github.com/rust-lang/rust/issues/82780">#82780</a> (i.e. streaming the depgraph) once it is rebased. <span class="user-mention" data-user-id="125250">@Wesley Wiser</span>, you are currently assigned, so please let me know if you have any objections or want to take a closer look yourself.</p>



<a name="232520209"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/232520209" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Wesley Wiser <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#232520209">(Mar 31 2021 at 00:52)</a>:</h4>
<p>I haven't had time to look closely at it but the description and perf looks good to me. Thanks for reviewing <span class="user-mention" data-user-id="124287">@mw</span>!</p>



<a name="232544791"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241847-t-compiler/wg-incr-comp/topic/Changes%20to%20the%20dep-graph%20on-disk%20representation/near/232544791" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> mw <a href="https://rust-lang.github.io/zulip_archive/stream/241847-t-compiler/wg-incr-comp/topic/Changes.20to.20the.20dep-graph.20on-disk.20representation.html#232544791">(Mar 31 2021 at 07:00)</a>:</h4>
<p>Thanks, <span class="user-mention" data-user-id="125250">@Wesley Wiser</span>! I just r+ed it.</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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